I am using Win7. I don't know what version of Adobe Reader I was using, but I went to the Adobe site and installed the latest version.
Then, I tested this file:
CanadianAimailRatesDec11-2013.pdf Canadian Air Mail Rates 1925-2011
And, tada! I was able to open and read the contents.
So, whatever changes you made (or perhaps I made to my computer) worked :)